Capture context for partial function defaults in closures

basex-core/src/main/java/org/basex/query/func/Closure.java

@@ -86,7 +86,7 @@ public Closure(final InputInfo info, final Expr expr, final Params params, final
     this.params = params;
     this.anns = anns;
     this.vs = vs;
-    this.global = global == null ? Collections.emptyMap() : global;
+    this.global = global == null ? new HashMap<>() : new HashMap<>(global);
     this.declType = declType == null || declType.eq(Types.ITEM_ZM) ? null : declType;
     this.name = name;
   }
@@ -128,6 +128,7 @@ public Expr compile(final CompileContext cc) throws QueryException {
     compiled = true;
 
     checkUpdating();
+    captureContextIfNeeded(cc);
 
     // compile closure
     for(final Entry<Var, Expr> entry : global.entrySet()) {
@@ -147,6 +148,20 @@ public Expr compile(final CompileContext cc) throws QueryException {
     return optimize(cc);
   }
 
+  /**
+   * Captures the context value if this closure wraps a static function call whose omitted default
+   * arguments depend on the context. This can happen for partial function applications.
+   * @param cc compile context
+   * @throws QueryException query exception
+   */
+  private void captureContextIfNeeded(final CompileContext cc) throws QueryException {
+    if(!(expr instanceof StaticFuncCall sfc)) return;
+    final Var var = new Var(new QNm("ctx"), Types.ITEM_ZM, cc.qc, info);
+    final VarRef ref = new VarRef(info, var);
+    final InlineContext ic = new InlineContext(null, ref, cc);
+    if(ic.inlineOrNull(sfc) != null) global.put(vs.add(var), new ContextValue(info));
+  }
+
   @Override
   public Expr optimize(final CompileContext cc) {
     cc.pushScope(vs);

basex-core/src/test/java/org/basex/query/ast/FuncItemTest.java

@@ -56,6 +56,18 @@ public final class FuncItemTest extends SandboxTest {
     );
   }
 
+  /** Checks that partial functions can use default parameters with context value. */
+  @Test public void partAppContextDefault() {
+    query("declare function f($a, $b:= .) { $a + $b }; 1!f(?)(2)", 3);
+    query("declare function f($a, $b:= 3 + .) { $a + $b }; 1!f(?)(2)", 6);
+    query("declare function f($a, $b:= <a>3</a>/. + .) { $a + $b }; 1!f(?)(2)", 6);
+    query("declare function f($a, $b:= .) { $a + $b }; let $v := 1!f(?) return 2!$v(3)", 4);
+
+    error("declare function f($a, $b:= .) { $a + $b }; f(?)(2)", NOCTX_X);
+    error("declare function f() {.}; 1!f() ", NOCTX_X);
+    error("declare function g($x := .) { $x }; let $f := fn() { g() } return 1!$f()", NOCTX_X);
+  }
+
   /** Checks that the Y combinator is pre-compiled. */
   @Test public void yCombinatorTest() {
     check("function($f) {" +